Many different applications may use a control system to govern the operation of a controllable mechanism. The control system may control the mechanism based on one or more input signals that may be received from an input mechanism or from sensors. These input signals may include information such as, for example, operational instructions from an operator, that indicate a desired operation of the controllable mechanism. The control system may process these input signals and deliver an appropriate command signal to the mechanism. The command signal may, for example, result in an increase or decrease in the operational speed of the controllable mechanism.
As described in U.S. Pat. No. 6,559,612 to Baumgarten, a control system may be programmed to control the rate at which a particular command is applied to the associated mechanism. The '612 patent describes a control system that controls the motion of a steering mechanism in response to instructions from an operator. The control system assigns a rate limit to the operation of the steering mechanism. The rate limit defines an acceptable rate of change in the operation of the steering mechanism over a given time period. The control system compares the instructions from the operator and, if the requested operation exceeds the rate limit, limits the requested operational change to be within the defined rate limit.
In some applications, however, the control system may receive several different inputs that may impact the operation of a controllable mechanism. For example, a vehicle, such as a work machine, may include several input mechanisms that allow an operator to control the motion of the vehicle. A manipulation of any one of these input mechanisms, which may be, for example, a joystick, a speed-up button, a speed-down button, or a brake pedal, may act to alter the operation of a power source and transmission on the vehicle.
In these types of applications, it may be desirable to apply a different rate limit to the transmitted command signal depending upon the input source of the instruction. For example, in a work machine, it may be desirable to allow the work machine to accelerate at one rate in response to a manipulation of a joystick and to accelerate at a second rate in response to a manipulation of a speed-up button. This may be accomplished by assigning a different rate limit to each input source.
In some circumstances, the operator may cause multiple, conflicting operational instructions to be transmitted to the control system. For example, the operator may step on the brake and move the joystick to a forward position at substantially the same time. This may cause two conflicting operational instructions to be transmitted to the control system. The control system may not process the conflicting commands properly, which may result in an unexpected operation. For example, the work machine may start to move when the operator expects the work machine to remain stationary.
The control system of the present disclosure solves one or more of the problems set forth above.